In 3rd Generation Partnership Project (3GPP), High Speed Uplink Packet Access (HSUPA) is prescribed in order to achieve high speed packet communication of an uplink (UL) which is a direction from a mobile station (UE: User Equipment) to a wireless base station (Node-B). It is to be noted HSUPA is sometimes called Enhanced UpLink (EUL) in order to avoid possible confusion with High Speed Downlink Packet Access (HSDPA).
In EUL, there is a tendency that the instant transmission power of the UE becomes higher in order to enhance the transmission rate of the uplink. Therefore, there is a tendency that also the interference power between neighboring cells in a cellular system becomes higher.
Therefore, between cells (Node-B) for supporting EUL, several means for suppressing the interference level of a UE positioned in the proximity of a boundary of a cell may be provided on the network level.
For example, in Patent Document 1 specified hereinbelow, a base station is disclosed which carries out communication with a mobile terminal existing in a subordinate cell and carries out control for reducing the interference from mobile terminals existing in neighboring cells.
The base station measures the total interference power received from mobile terminals in all of the neighboring cells, and transmits, if the total interference power is higher than a preset value, a request for reducing the interference to the base stations of all of the neighboring cells.
Each of the base stations receiving this interference reduction request discriminates mobile terminals which may possibly apply the interference to the base station of the requesting source and temporarily decreases the transmission rate of upward data of the mobile terminals or temporarily stops transmission of upward data to reduce the interference.
Patent Document 1: pamphlet of International Publication No. WO2006/087797
However, in the conventional technique described above, it is premised that both base stations (Node-B) which provide neighboring cells with each other support communication by EUL and each of the base stations can identify all of wireless channels prescribed by EUL and besides the total interference power of the UL can be measured by the individual neighboring base stations in regard to all neighboring cells.
In particular, the conventional technique does not anticipate a case wherein an EUL supporting base station and an EUL non-supporting base station which does not support part or all of wireless channels additionally prescribed by EUL exist in neighboring cells. Such a mixture configuration as just described may possibly appear within a transition period of system switchover from an old to a new system.